Switchboard system



July 10, 1945. L. F. PORTER SWITCHBOARD SYSTEM Filed Feb. 29, 1944 hm. @HMM goku CGI . m. @Nvu w A TTORNE V Patented July 10,`v1945 a i This :invention relates `tellephone switchfboards and" more particularly to a methoduand means for converting rtliexscord cireuitsf` of` a; toll switchboard, normally arrangedfor thedi'rect in,- terconnection ofl two ringf-downgitoll lineslor a circuit, butinot two itrunkfcircuitaito, permit the cuits.` i `A feature of the invention resides in theprooperative` interconnectionlof `two such'trunkcirf vision `of x operator, controlled* means" associated with onegof two-adjacent cord, circuits forpdis-` `connecting thealternating. current ringf-up relays usually inwbridge of eachofthetwo cordcircuits and-connecting acondenser between the two tip conductors of :the adjacent (cords, and another condenser betweenmthe corresponding two ring 1 conductors, wherebyafdirect current supervision interconnecting,circuit for two trunk circuits is provided between the so-called rear or trunk plugs of the twocord circuits. When two cord circuits are so converted and connected their front cords remain idle. The drawing shows the `normal complement of cord circuits, I to 6, inclusive, usually provided at a so-called CLR (combined line and recording) toll operators position which cords are arranged to be converted under controlnf the operator in accordance with the present invention, the normal circuit condition of which (unoperated condition of the operators'control means), being the' `toll` line .fand a direct current` supervisonntrunk ,a

s rrerrnonim'srs'rEM` New lays, as for example `for cords I t and` for l `cords 3 and 4, etc.

scribed condition exists, i. e., the unoperatedcondition of `switches SMS2, S3and,relays `1`\'.I.1 R2 i and R3, thecord circuits are conditioned `foriiise in `the usual manner, i. e., for answeringeither Va trunk or toll line with 1the rear g cord and; extending a calling trunk to a toll lineor a callingtoll rent Supervision relay (TRI `for ezieltrllfle)ti.111`

lineto a trunk, or anothergtoll line, by` means of the front `cord ofthe paiigbut duetoithecfact that each cord circuit V,has only` onegjdirect cur-r bridge thereto it is not practicable",toconnect two trunks toeethenfor thcreasem that ,.011 Y Q11@ supervisory signal relayis prov ided A: l .Infcaseit is desired; tojinterconnect two arrangement usually provided at such operators position, i. e., cords each having one direct current trunk supervision relay (TRI, etc), and one alternating current ring-up relay (RUI, etc.) in series with a condenser, bridged thereacross, to-

gether with other well-known circuit arrangements not shown such as talk and ringing key apparatus and circuits, supervisory lamp circuits, etc., which have no direct relation to the ,present invention.

With further reference to the drawing, manually operated conversion switches SI, S3 and S5 are mounted on the face plates of the key assemblies KI, K3 and K5 of cord pairs I, 3 and 5and Supervision typename Operatowlllyansw With the rear cord of one of y two adjacent idle` cord i aipairs, cord pair I for example, and after operating the associated switch SI associated with thatzcord i pair proceed to extend the connection to the called trunk over the rear cord of cord pair 2.

Whenswitch SI is operated relay RI operates and opens its right-hand contacts thereby disl connecting the bridged ring-up relays RUI and RU2 from their normal connection across their respective cord circuits, for the purpose oi remo`v` ing all unnecessary bridges from the cords to pre-` vent any possible eiecton transmission, A

Operation of relay RI, for examplef also connects, over `its leftfhand` contacts, a condenser TCI between the tip conductor ofcord pair I and the tip conductor ot cord pair 2 and alsoafsecond` i condenser RCI between the `ring conductors of the same two pairs of cords.

From the foregoing it will therefore benoted `-that with switch SI, `for example, operated, `a

switching relays RI, R3 and R5` are associated with and controlled by switches SII, `S3 and S5,

respectively.

. Whenthese switching relays, RI for example, i

are in their normal 0r released position, i. e., when the contacts of switch SI for example arenot closed, the associated ring-,up relays RUI, etc. are

connected in bridge of theirassociated cord circuits in series withI the corresponding condensers CI, C2, etc., over contacts of the respective R. re-` speech transmission path extends frorn the rear plug of cord pair I over the left-hand'contacts of-relay RI and condensers TCI `and RCI to the rear plug of cord pair 2, but these condensers prevent direct current flowing iromone rear cord to the `other and hence when the two trunks are interconnected in this manner the direct current supervisory relay TRI will be, .controlled over the 3trunk connected to the rear "plug of cord pair I `and relay TR2 over the trunk connected tothe rear plug of cord pair 2. i i

As before mentioned when `two cord circuits are convertedand both rear plugs are .connected to trunks, the two frontcords remain idle. A1. though `it will be noted that a trunk to trunk )connection can also be established `over the twofront cords, with the two rear cords remaining idle, but under this condition, as when the rear cords only are used, the same trunk supervisory relays, i. e., TRI, TR2, for example, function vto control the supervisory lamps associated with the rear cords which could be confusingr to an operator when the establishment and supervision of trunk toy trunk connections forms only a minor,

portion of ,her dutieswhich principally lc onsist in establishing connection between trunks and toll lines, or between two toll lines, which interconnections are effected by the front and rear cords-of single cord circuits.

What is claimed is: ,l 1. In a telephonesystem, a switchboard hav,-

ing a plurality of dilrect4 current 'supervision trunk lines and yring-down toll lines terminating thereat, two cord circuits at saidA switch-V board, each cord circuit having front land rear cords, a direct current responsive supervisory signal device and an alternating current respon- .tors of `.said two cord circuits.

a front and a rear cord and adapted to operatively connect one of said alternating current supervision lines and one of said direct current supervision lines but not two of said direct current supervision lines, and means for arranging said pair of cord circuits to provide for the operative connection of two of said direct current supervision lines over the rear cords of said two cord circuits, said z'neans'comprising a pair of condensers and an operator controlled switch, said switch being arranged when operated to connect said condensers between the respective-conduc- 3. In atelephone switchboard, an operators position a pairofrcord circuits thereat each having tip and ring `conductors, a pair of condensers associated with said pair of cord circuits and f commonI thereto,poperator controlled switching sive supervisory signal device in bridge vof eachv cord circuit intermediate the end thereof,-and means foriarranging saidtwo-cord circuits to ipern'llt the interconnection of two of said direct current supervision trunk lines over the two rear cords of said two cord circuits, Asaid means .comprising a pair of condensers and operator controlled switching means associated with one of said cord circuits for disconnecting the alternating current devices in both of said cord circuits -and interconnecting the respective tipv and ring conductors of said two cord circuits through said condensers.y I

2. In a telephone switchboard, an olieratorrs` position, a plurality of direct current supervision lines and ay plurality of alternating current supervision lines `terminating at said position, a pair ofl two conductor .cord circuits each having means atl said position associated with and comm'onto" said pair of cord circuits adapted when `operatedeto connectione of said condensers be- `connect one of said. condensers between the tip conductors of. said two adjacent cord circuits, and to `connect the other-.condenser between the two respective ring conductors. y Y Y A A f i t LESLIE F, PORTER. 

